REV106617

• Permit No: C1980007
• IBM Index Class Name: Revision
• Doc Name: FORMAT AND SUPPLEMENTAL INFORMATION
• Type & Sequence: RN1
• Media Type: D
• Archive: No

• spring is perennial and exhibits a relatively high rate of discharge on the
order of 25 to 100 gpm, it is conceivable that the spring is controlled by
fracture flow. The ionic composition and TDS levels are unlike the water
quality measured in groundwater wells on the property with the exception of
SOM-80, a Barren Member well in Sylvester Gulch. Since Sylvester Gulch is
also [bought to be fracture controlled. It may be that the higher calcium,
magnesium and sulfate composition of these waters may be a feature of
fracture flow.
All other springs below the F-seam are outside the area of potential
influence usually across surface drainages from mining activity.
New Table 2.8.S.L, "Worst Case Hydrologic Impact Evaluation," presents the
worst case analysis of spring depletions broken down by watershed and by S-
yr mining period. In compiling this table the highest flows recorded for
each potentially impacted spring during the Spring and Fa11 were taken as
being representative of a wet year. Similarly, the lowest recorded flows
during these periods were assumed to be representative of a dry year.
Under worst case conditions all potentially effected springs will be
totally depleted. New Table 2.8.5.E includes the calculated peak seasonal
and expected perennial mine inflows by year and watershed from the analysis
described in the answer to question V.A.9 and summarized in Table 2.S.S.J.
Table 2.8.5.E shows that the predicted mine inflows are generally within or
slightly higher than the range of the predicted total peak spring
depletions from each watershed. This lends credibility to the mine inflow
• analysis calculations which were based on observed mine inflows and
assumptions concerning potential interconnection with shallow ground water
flows that are believed to be the major source of spring flows.
Measured spring flows have been plotted through 85 and are provided as
attached Figures 2.8.1.D.1 through 2.8.1.D.19. Included are two springs,
G- and G-12, [hat have data covering pre-mining impact and post mining
impact periods. Examination of the measured flows of spring G- reveals an
increase in flow in 84 compared with flows in the 3 previous years. On the
other hand, the flows from spring G-12 during the years 84 and 85 are
slightly less than the flows during the Years 81, 82 and 83 but exceed the
flows measured in 79 and 80. From these data it is difficult to assess
whether any changes in flow has occurred as a result of mining which was
projected to have first had an impact on these springs near [he end of 83.
I[ is clear from these data that the degree of impact, if any, is much less
than the worst case assumption of total depletion that was used in
developing the estimates for Table 2.S.S.L.
Even if the flow in a spring were depleted as a result of mining, the
depleted flow would be expected to either re-issue at another location or
become mine inflow.
Table 2.8.5.E also contains a comparison of the worst case projections of
spring depletions and mine inflows with streamflow data representative of
wet year and dry year snowmelt flows and wet year and dry year baseflows
for the corresponding basins. A11 streamflow estimates in Table 3 with the
exception of Dry Fork Minnesota Creek were derived from gaging stations
• located on the streams below the coal outcrop. Since flows in the lower
V-22